Amendment 66 went down Tuesday 66 percent to 34 percent, according to still-unofficial results from the Colorado Secretary of State. Backers vastly outspent opponents of the measure, but the limited public polling in the state before Nov. 5 showed serious apprehension among voters, particularly those informed of the details of the tax hike.

The tax increases in Amendment 66 would have funded an education overhaul package passed by Democratic state lawmakers on a party-line vote earlier this year. The legislation, Senate Bill 213, would have poured money into early childhood education, boosted spending for districts with higher percentages of poor students and English-language learners, provided money for teachers' professional development and evaluation, created a grant pool designed to spur innovation and increase funding for charter schools. In exchange, income tax rates would have increased from 4.63 percent to 5 percent on the first $75,000 of earnings and to 5.9 percent beyond that.

Opponents pointed out that the tax increase would be concentrated among a limited number of counties that wouldn’t stand to gain as much as their poorer neighbors. But SB213 did include a “hold-harmless” provision that prevented any county from sliding while giving at least minimum annual boosts. Amendment 66 detractors, which included the conservative Americans For Prosperity, also warned of damage to small-business owners, many of whom file their taxes as individuals.

AFP, which is funded by the wealthy industrialist Koch brothers, sought to paint the overhaul as a boon for teacher unions that doesn’t come with reforms like greater school choice.

“Passing Amendment 66 would have gravely wounded the state’s economy and business climate, while rewarding a reform-resistant education system with an un-earned windfall,” said the state’s director in a statement.

The main group backing the measure did not issue a statement following Tuesday’s vote. Chief supporters included a Democratic state senator who previously worked as a principal as well as unions, some business groups and some charter school backers. The campaign brought in money from the likes of Walmart founder Ben Walton and former New York City Mayor Michael Bloomberg.

In the end, even counties that stood to gain the most voted against Amendment 66. A few counties have not yet reported their results, but as of Wednesday morning only Boulder and Denver counties approved of the measure, and only by a thin margin. Both of those counties would have shouldered much of the tax burden, but both would have seen boosts in spending per student, albeit a small bump in the case of Boulder. Denver would have gained about $1,000 in per-pupil spending.